Axial flow regenerative heat exchangers



Feb, 20, 1968 H. BRANDT 3,369,593

AXIAL FLOW REGENERATIVE HEAT EXCHANGERS Filed Oct. 4, 1965 5 Sheets-Sheet l T 1'5- 1 I]; J

H. BRANDT AXIAL FLOW REGENERATIVE HEAT EXCHANGERS Feb. 20, 1968 3 Sheets-Sheet 5 Filed Oct. 4, 1965 United States Patent 3 Claims. Cl. 165-40) ABSTRACT OF THE DISCLOSURE The deformation of and stresses in the mass of plates in rotary regenerative heat exchangers as a result of the temperature differences-of the hot and cold ends can be minimized by constructing the regenerator portion as an axial flow structure which comprises a plurality of annular portions concentric with each other together with means for interconnecting the annular portions in such a way that each portion is supported relative to each other portion and in such a way as to provide an annular gap between adjacent portions and free adjustability of each annular portion independently of each other annular portion.

This invention relates to rotary regenerative heat exchangers of the kind which includes, inter alia, a substantially cylindrical heat exchange member, referred to hereinafter as a regenerator, which comprises a casing containing a mass of plates or tubes, hereinafter referred to, for convenience, as plates, which provide passages through the regenerator, hot gas being led through the said passages in one direction, substantially parallel to the axis of the regenerator, in order to give up its heat to the said mass, whereafter air is led through the same passages in the opposite axial direction in order to pick up the heat from the said mass. In some cases the regenerator rotates about its axis, while the means for supplying said air and hot gas to the regenerator, and for leading the cooled gas and heated air from the regenerator are stationary; in other cases the regenerator is stationary while the said air conducting means rotate about the projected axis of the regenerator.

The mass of plates in the regenerator acquire a higher temperature at the axial end (which will be referred to as the hot end) of the regenerator to which the hot gases are supplied and from which the heated air is withdrawn, than at the opposite axial end (which will be referred to as the cold end) of the regenerator from which the cooled gas is withdrawn and the cold air enters. These temperatures differences in the regenerator cause deformation of and stresses in the mass of plates and the regenerator casing which have had to be allowed for, in the design of the heat exchanger, by expensive construction measures. With the present tendency for rotary regenerative heat exchangers to increase in size considerably (some regenerators have a diameter of approximately 12 meters, and an axial height of approximately 2 meters), the stresses therein become very considerable.

In consequence of such tendency of the regenerator parts to deform, and of restoring forces applied thereto, the regenerator tends to assume the form of a calotte, with a concave surface at the cold end and a convex surface at the hot end.

Consequently, the means for sealing the adjacent, relatively rotating, end surfaces of the regenerator and of the air conducting means, to prevent undue leakage of gas and air therebetween, become very complicated in design and construction. 1

The object of the present invention is to provide improvements in regenerators of rotary regenerative heat 3,369,593 Patented Feb. 20, 1968 exchangers whereby to minimise the deformation effects of the differential temperatures of cold and hot ends thereof.

According to this invention, a substantially cylindrical regenerator of a rotary regenerative heat exchanger is characterised in that it is formed of a plurality of annular portions which are concentric with each other and are spaced apart radially to provide an annular gap therebetween.

Referring to the accompanying drawings:

FIG. 1 is a diagrammatic sectional elevation of a rotary regenerative heat exchanger;

FIGS. 2 and 3 are diagrammatic sectional elevations of a regenerator which has been subjected to the differential temperatures;

FIG. 4 is a diagrammatic sectional elevation of a rotary regenerative heat exchanger embodying a regenerator according to this invention;

FIG. 5 is a diagrammatic end view of the regenerator included in the heat exchanger shown in F164, looking along the axis thereof;

FIG. 6 is a diagrammatic sectional elevation illustrating, in an exaggerated manner, the deformation of the regenerator shown in FIG. 4.

FIG. 7 is a fragmentary enlarged diagrammatic sectional elevation of part of FIG. 4; and

FIG. 8 is a fragmentary plan view corresponding to FIG. 7.

Referring to FIG. 1, which shows a known form of rotary regenerative heat exchanger, a cylindrical regenerator 11 contains a mass 12 of heat exchange plates. Hot gas is supplied to the hot end 13 of the regenerator, in the direction of the arrow 14, through a duct 15, and the gas, after being cooled by transfer of its heat to the mass 12 of plates, leaves the cold end 16 of the regenerator and is led away through a duct 17.

Cold air is supplied to the cold end 16 of the regenerator, in the direction of the arrow 18, through a duct 19, and the air, after being heated by transfer of heat from the mass 12, leaves the hot end 13 of the regenerator and is led away through a duct 20.

The regenerator 11 may rotate around its axis 21, while the ducts 15, 17, 19 and 20 remain stationary, or the regenerator 11 and the gas ducts 15 and 17 may be stationary while the air ducts 19 and 20 rotate about the projected axis 21. In either event there is relative rotation between the regenerator 11 and the air ducts 19 and 20.

Due to different temperatures at the hot end 13 and the cold end 16 of the regenerator, there is greater expansion at the hot end 13 than at the cold end 16. If such expansion were not impeded (by thecasing and other constructional elements of the heat exchanger), the regenerator would tend to take up the form shown, in an exaggerated manner, in FIG. 2. However, due to restoring forces which operate upon the regenerator, t-he regenerator cannot assume the form shown in FIG. 2, and therefore assumes the form of a calotte, shown in exaggerated form in FIG. 3.

In order to minimise the deformation of the regenerator 11 to the form shown in FIG. 3, the regenerator is made, according to the present invention, in the form shown, by way of example, in FIGS. 4 and 5. The regenerator is constructed of a plurality of separate concentric annular portions. In FIGS. 4 and 5, two annular regenerator portions 22 and 23 are shown, but there may be three or more such annular concentric regenerator portions.

In FIGS. 4 and 5, an inner annular regenerator portion 22 is surrounded by an outer annular portion 23, the two portions being separated from each other, but connected to each other, so that the two portions are supported relatively to each other, by connecting means 24. Consequently, the two annular portions 22 and 23 will expand and deform independently of each other; they may each assume a substantially calotte formation, and such deformation may assume the form shown, in exaggerated manner, in FIG. 6.

In FIG. 6 it will be seen that the concave cold end surface 16 of the regenerator is broken up (compared with the form shown in FIG. 3) into several separate concave surfaces each of which is of less depth (axially of the regenerator) than the depth of the concave cold end surface shown in FIG. 3; the convex hot end surface 13 of the regenerator similarly is broken up into several separate convex surface portions.

The effect of this arrangement of the regenerator is that the sealing means (shown diagrammatically at 25 and 26) between the regenerator and the air ducts, and between the regenerator and the surrounding casing of the heat exchanger, can more efiiciently minimise any leakage of gas or air.

The connecting means 24 between the annular concentric regenerator portions 22 and 23 are shown in FIGS. 7 and 8 which are an enlarged fragmentary sectional elevation and plan respectively. A bracket 27 on the inner face of the outer annular portion 23 is engaged by another bracket 28 on the outer face of the inner annular portion 22, and bolts 29 pass through the two brackets. There are four sets of interengaging brackets 27 and 28 disposed in the annular gap 30 between the concentric annular portions 22 and 23, at intervals of 90 degrees; however, there may be any number, more than two, of such sets, spaced around the regenerator at suitable angular intervals. Thereby, the outer annular portion 23 of the regenerator, which portion is itself supported on fixed structures 31 (FIG. 4) of the heat exchanger, in turn supports the inner annular portion 22. Such an arrangement is sufficient if the regenerator is stationary. If the regenerator rotates, then horizontally disposed bolts may have to be disposed between the brackets 22 and 23 (which will then have to be provided with vertical lugs to receive the bolts) to providedrag means so that a rotary drive applied to one of the annular regenerator portions is transmitted to the other portion; alternatively, interengaging claw devices may be provided between the two annular portions of the regenerator so that a rotary drive may be transmitted from 4. one portion to the other. Except at such interengaging connecting means 24, the two annular regenerator portions 22 and 23 may move independently of each other.

At suitable angular intervals around the annular gap 30 there are disposed vertical ribs 32 extending inwardly, parallel to the axis, of the regenerator, from the regenerator portion 23 into channels 33, also parallel to the axis of the regenerator, secured to the portion 22 to provide substantial seals against the circumferential flow of gas or air in the gap.

What I claim and desire to secure by Letters Patent is:

1. An axial flow regenerator for a rotary regenerative heat exchanger which comprises a plurality of annular regenerator portions concentric with each other and carrying a heat storage mass and means for interconnecting said annular portions so that each portion is'supported relative to each other portion and so that an annular gap between adjacent annular portions is provided and each annular portion is freely adjustable independently of each other annular portion,

2. An axial flow regenerator according to claim 1 wherein said interconnecting means is disposed in the gap between each separate concentric annular portion and comprises brackets attached at one face to their respective annular portions and attached at their common face, by

means which secure the adjacent annular portions in a supporting manner to one another and allow each annular portion to move independently of each other annular portion.

3. An axial flow regenerator according to claim 1 wherein said interconnecting means overlap one another to prevent circumferential flow of fluid in said gap.

References Cited UNITED STATES PATENTS I 2,432,198 12/1947 Karlsson et al 0 -40 2,503,651 4/1950 Alcock 1658 2,944,798 7/1960 Muller 165-10 3,216,486 11/1965 Hall et al. 1658 3,301,316 1/1967 Mason 16510 X ROBERT A. OLEARY, Primary Examiner.

A. W. DAVIS, JR., Assistant Examiner. 

